1. Field of the Invention
The present invention relates to systems and methods for providing caller identification information to a called party.
2. Background of the Related Art
According to the online dictionary Wikipedia.com, caller ID (caller identification, CID, or more properly calling number identification) is a telephone service, available on plain old telephone service (POTS) lines, that transmits a caller's number to the called party's telephone equipment during the ringing signal, or when the call is being set up but before the call is answered. Where available, caller ID can also provide a name associated with the calling telephone number, for a higher fee. The information made available to the called party may be made visible on a telephone's own display or on a separate attached device.
Caller ID may be used to track down or limit the impact of prank calls, telemarketers, and other intrusions. However, it can also impede communication by enabling users to become evasive. The concept behind caller ID is the value of informed consent. However, caller ID may also raise issues about personal privacy or facilitate caller ID spoofing.
Caller ID is made up of two separate pieces of information: the calling number and the billing (or subscriber) name where available. When an originating phone switch sends out a phone number as caller ID, the telephone company receiving the call is responsible for looking up the name of the subscriber in a database. To look up the name associated with a phone number, the carrier in some instances has to access that information from a third party database and some database providers charge a small fee for each access to such databases. To avoid such charges, some carriers will report the name as unavailable, or will report the name as “(city), (state)” based on the phone number. For 800 numbers, they may report a string such as “TOLLFREE NUMBER” if the name is not available in a database.
What is displayed as caller ID also depends on the equipment originating the call. If the call originates on a POTS line (a standard loop start line), caller ID is provided by the service provider's local switch. Since the network does not connect the caller (i.e., the calling party) to the callee (i.e., the called party) until the phone is answered, generally the caller ID signal cannot be altered by the caller. Most service providers however, allow the caller to block caller ID presentation through the vertical service code *67. A call placed from behind a private branch exchange (PBX) has more options. In the typical telephony environment, a PBX connects to the local service provider through PRI trunks. Generally, although not absolutely, the service provider simply passes whatever calling line ID appears on those PRI access trunks transparently across the Public Switched Telephone Network (PSTN). This opens up the opportunity for the PBX administrator to program whatever number they choose in their external phone number fields.
Still further, internet protocol (IP) phone services support PSTN gateway installations throughout the world. These gateways egress calls to the local calling area, thus avoiding long distance toll charges (a key feature of IP services). IP phone services also allow a local user to have a number located in a foreign exchange, such as a New York caller could have a Los Angeles telephone number. When that user places a call, the calling line ID would be that of a Los Angeles number although they are actually located in New York.
With cell phones, there are issues with passing calling line ID information through the network. Cell phone companies must support interconnecting trunks to a significant number of wireline and PSTN access carriers. In order to save money, cell phone carriers may not purchase the North American feature Group D or PRI trunks required to pass calling line ID information across the network.
In the United States, caller ID information is sent to the called party by the telephone switch as an analog data stream (similar to data passed between two modems), between the first and second rings, while the telephone unit is still on the hook. If the telephone call is answered before the second ring, caller ID information will not be transmitted to the recipient.